The present invention relates to reclining and fold-flat mechanisms for the passenger seats in a vehicle. More specifically, the invention relates to a mechanism that allows a seat to be reclined or folded flat, and also, serves to lock the seat in its reclined or upright position.
Many seat reclining mechanisms are known and used in the automotive industry. In some applications a fold-flat feature is provided that allows the seat back to be folded forward to a flat position substantially parallel to the seat bottom. Such an arrangement enhances cargo space and is commonly found in vans and sport utility vehicles. Some amount of fold over is also required in two door vehicles to allow access to the rear seats or rear compartment area. In addition it is often desirable to provide some degree of recline adjustment. In some applications, the second row seating is divided in a 60/40 split arrangement in which 60% of the second row seating folds and reclines independent of the remaining 40%. This design provides additional flexibility and individuality in the adjustment the passengers"" seating, thus providing a more comfortable seating position.
The federal government has imposed standards for seats having a reclining and fold-flat feature. These standards include requiring that the seat back not be pivotable relative to the seat except during actuation of a release mechanism. The federal regulations further require that the mechanism for locking the seat-back in a stationary position be capable of withstanding the load exerted on the seat-back when the passenger is thrusted forward during sudden braking or in a collision. These standards are particularly important in the case where the safety belt is secured to the seat-back thereby casting a significant load on the back of the seat during rapid deceleration.
The currently available seat reclining and folding mechanisms present several disadvantages. First, the hardware is typically complex and consists of many close fitting interacting parts. This complexity contributes to the difficulty in production, assembly and maintenance of the mechanisms; ultimately increasing production costs, as well as, maintenance and repair costs.
For instance, many reclining assemblies, such as the system described in U.S. Pat. No. 4,634,182 to Tanaka, employ two separate mechanisms: (1) a hinge mechanism for reclining the seat-back backwards, and (2) a separate inertia operated lock system for permitting the seat to fold forward and to lock the seat back in the upright position. The existing inertia operated lock systems, such as that employed in Tanaka, are often based on a pendulum system that locks the seat in its upright position upon a sudden forward tilting motion of the seat. In these assemblies the hinge mechanism remains unlocked even when the seat is occupied and while the vehicle is in operation. Only when the pendulum swings forward due to deceleration does the inertia operated lock operate to lock the seat-back in the upright position.
These arrangements pose many disadvantages. First, these assemblies comprise two separate mechanisms; a hinge mechanism and an inertia operated lock mechanism, each having complex multiple parts. This ultimately results in an increase in the cost of production. Moreover, the use of multiple components increases the chance of malfunction and increases the cost of maintenance and repair.
Other seat recliner mechanisms employ complex parts such as multiple gears or multiple hinges. These multiple parts create a complex mechanism that is difficult to produce and difficult to repair. Furthermore, the multiple gear systems have a greater chance of getting gummed up, thus decreasing their effectiveness.
In light of the disadvantages existing in the current seat reclining mechanisms a need remains for a seat reclining and fold-flat mechanism that employs one mechanism to recline the seat-back, fold the seat-back flat, and lock the seat-back in an upright position. In addition there is a need for such a system that is easy to operate, light weight, compact and that can be manufactured at a reasonable cost. Furthermore, such a system must be capable of maintaining the seat-back in the locked position when the seat-back is subjected to the force of a passenger being thrust forward during sudden deceleration or collision.
In order to address the needs unfulfilled by prior devices, the present invention contemplates a mechanism for use in a vehicle seat that permits reclining the seat-back, allows folding the seat-back flat, and securely locks the seat in an upright or reclined position.
In one embodiment, the mechanism includes an arm attachable at one end to the seat-back, and pivotably attachable at an opposite second end to the frame. The arm, and thereby the seat-back, is pivotable relative to the frame. A pawl is provided having a pivot end pivotably attachable to the frame and a gripping end. The pawl is movable between a locked position, in which the gripping end engages the arm to prevent the arm from pivoting, and a released position, in which the gripping end is free from the arm, thereby permitting the arm to pivot. The mechanism also includes a means for releasably securing the pawl in its locked position.
In one feature of the invention, the means for releasably securing the pawl in its locked position includes a locking member. The locking member has a pivot end that is pivotably attachable to the frame and a bearing end. The locking member pivots between a supporting position and a freeing position. In the supporting position, the bearing end applies a force to the pawl to urge the pawl into its locked position. In the freeing position, the bearing end is free from the pawl allowing the pawl to pivot to its released position.
In another aspect of the invention, when the pawl is in its locked position, the gripping end of the pawl and the second end of the arm are locked in an interdigitated engagement. The interdigitated engagement can include a number of teeth and notches defined on both the gripping end of arm and the second end of the arm. To provide adjustability in the recline angle, the number of teeth and notches defined on the arm can be greater than the number of teeth and notches defined on the gripping end of the pawl.
A further aspect of the invention includes a means for pivoting the locking member between its supporting position and its freeing position. The means for pivoting the locking member can include a torsion bar assembly. The torsion bar assembly includes a torsion bar having a working end connected to the locking member of a mechanism attached to one side of the seat, and a slave end connected to the locking member of a mechanism attached to the other side of the seat. A cable control arm is attached to the torsion bar adjacent the working end. A cable is provided that connects at one end to a lever and at the other end to the frame. The cable has a first slack condition and a second taut condition. When the lever is engaged, the cable changes from its slack condition to its taut condition. A cable conduit is attached to the cable and operates to pivot the control arm when the cable is in its taut condition, thereby turning the torsion bar and pivoting the locking member.
It is an object of the invention to provide a mechanism that reclines the seat-back, folds the seat-back flat, and locks the seat-back in an upright or reclined position.
It is a further object of the invention to provide a fold-flat seat reclining mechanism that is capable of maintaining the seat-back in the locked position when the seat-back is subject to the force of a passenger being thrust forward during sudden deceleration or collision.